FORCES

Question 1

force defintiion

Answer 1

a push or pull that acts on an object due to its interaction with another object

Question 2

are forces vector or scalar quantities

Answer 2

VECTOR
has both magnitude and direction

Question 3

what is normal contact force

Answer 3

The normal contact force is the force that acts at 90° (a right angle) to a surface when something touches it. It pushes back up when an object presses down.
EQUAL & OPPOSITE FORCE

Question 4

What is electrostatic force

Answer 4

force between two charged objects

Question 5

scalar

Answer 5

only have magnitude
e.g distance mass temp time speed

Question 6

vector

Answer 6

both magnitude and direction
e.g velocity acceleration momentum force displacement

Question 7

difference between distance and displacement

Answer 7

distance is scalar - has no direction

Question 8

what do free body diagrams show

Answer 8

all the forces acting on an object

Question 9

how to find resultant forces from free body diagrams

Answer 9

subtract the opposite forces

Question 10

what does it mean when an object is in equilibrium

Answer 10

has no resultant forces acting on it
all subtract to be 0

Question 11

what is resultant force

Answer 11

the overall force acting on an object, taking into account all the different forces acting on it.

Question 12

How do you find the magnitude and direction of a resultant force using a scale diagram?

Answer 12

Choose a scale (e.g. 1 cm = 10 N)

Draw each force to scale using a ruler and accurate angles (use a protractor)
➤ Place arrows tip-to-tail (not from the same point)

Draw the resultant force:
➤ From the start of the first arrow to the end of the last arrow
➤ This is the resultant — draw and label it

Measure its length with a ruler and convert it to a force using your scale

Measure the angle (from horizontal or vertical) using a protractor to find the direction

Question 13

deformation

Answer 13

a change in the shape of an object as a result of forces being applied to it.

Question 14

objects can

Answer 14

compress stretch or bend

Question 15

weight

Answer 15

the force acting on an object due to gravity

Question 16

elastic deformation

Answer 16

can return back to its original shape

Question 17

inelastic deformation

Answer 17

stays deformed - doesnt return to og shape

Question 18

extention of an elastic object is directly proportional to

Answer 18

the force applied , provided that the limit of proportionality is not exceeded

Question 19

hookes law

Answer 19

the directly proportional relationship between force & extension

Question 20

when does a non linear relationship happen between force & extension

Answer 20

when the limit of proportionality has been exceeded

Question 21

lower spring constant

Answer 21

object is more easily stretched

Question 22

moment

Answer 22

the turning effect of a force

Question 23

moment if the object is balanced

Answer 23

the total clockwise moment is equal to the total anticlockwise moment about that pivot

Question 24

The units for moment are:

Answer 24

newton metres nm

Question 25

what does a lever / a gear do

Answer 25

transmit the turning effect of a force

Question 26

How do levers transmit the rotational effect of a force?

Answer 26

Levers increase the distance from the pivot, so less force is needed to produce the same moment. They magnify the force and change its direction, helping lift heavy loads more easily.

Question 27

What is the benefit of using a lever?

Answer 27

Levers make it easier to do work by increasing the moment using a smaller input force over a longer distance.

Question 28

How do gears transmit the rotational effect of forces?

Answer 28

Gears transfer turning forces (moments) between shafts. They can change the direction, speed, and force of rotation depending on the size of the gears.

Question 29

What happens when a large gear turns a small gear?

Answer 29

The small gear spins faster, but with less force. Speed increases, force decreases.

Question 30

What happens when a small gear turns a large gear?

Answer 30

The large gear turns slower, but with more force. Force increases, speed decreases.

Question 31

The ratio of the turning effect of the two gears is proportional to the

Answer 31

ratio of the radius of the two gears.

Question 32

pressure

Answer 32

force per unit area

Question 33

the pressure in fluid causes

Answer 33

a force normal (at right angles) to any surface

Question 34

what is pressure in a liquid due to

Answer 34

the surrounding water molecules colliding with it weight of all the water above the object

Question 35

why is there a stronger pressure on objects fully submerged in water at the bottom of a collumn

Answer 35

pressure (due to weight) increases as the weight of water above is larger

Question 36

why is there more pressure eon an object that's in a denser liquid

Answer 36

more dense = larger mass per unit vol. = larger weight

Question 37

factors affecting pressure in a liquid

Answer 37

gravitational field strength density weight of water above

Question 38

why do objects float

Answer 38

upthrust force pushes object up & is stronger than its weight less dense than liquid = float

Question 39

why does an object sink

Answer 39

upthrust force is smaller than its weight which pulls it down more dense than water = sink

Question 40

Upthrust is caused by:

Answer 40

The pressure on the bottom of the object being greater than the pressure on the top of the object

Question 41

the atmosphere gets less dense with ....

Answer 41

increasing altitude

Question 42

what creates atmospheric pressure

Answer 42

air molecules colliding with a surface

Question 43

why is there less pressure as height increases

Answer 43

the number of air molecules and so the weight of air decreases as the height increases above ground level

Question 44

is speed scalar or magnitude

Answer 44

SCALAR

Question 45

is velocity scalar or vector

Answer 45

VECTOR

Question 46

distance / displacement = scalar / vector

Answer 46

DISTANCE = SCALAR DISPLACEMENT = VECTOR

Question 47

velocity =

Answer 47

displacement / time

Question 48

unit for velocity

Answer 48

m/s east/west/north/south

Question 49

walk / run / cycle speed

Answer 49

1.5m/s walk run 3m/s cycle 6 m/s

Question 50

speed of sound in air

Answer 50

330 m/s

Question 51

car / train / plane speed

Answer 51

25 m/s car 55 m/s train 250 m/s plane

Question 52

acceleration

Answer 52

rate of change in velocity

Question 53

negative acceleration =

Answer 53

decelleration

Question 54

terminal velocity

Answer 54

the maximum speed an object can reach when falling through a fluid (like air or water)

Question 55

how to find distance travelled off a velocity time graph

Answer 55

are underneath line

Question 56

factors affecting velocity

Answer 56

surface area (larger area for collisions to take place) velocity

Question 57

when does an object reach terminal velocity

Answer 57

air resistence = weight WHEN RESULTANT FORCE = 0

Question 58

newtons fist law

Answer 58

every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force

Question 59

inertia

Answer 59

the tendency of objects to continue in their state of rest or of uniform motion

Question 60

newtons second law

Answer 60

F = ma the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass

Question 61

inertial mass

Answer 61

a measure of how difficult it is to change the velocity of an object THE RATIO OF FORCE OVER ACCELERATION

Question 62

A moving object that has no resultant force acting upon it will:

Answer 62

continue moving at the same velocity

Question 63

newtons third law

Answer 63

whenever two objects interact, the forces they exert on each other are equal and opposite

Question 64

Anna hits a nail with a hammer. During the collision, a force is exerted:

Answer 64

on both the hammer and the nail

Question 65

stopping distance

Answer 65

the minimum distance required to stop a vehicle in an emergency (thinking distance + breaking distance)

Question 66

things affecting thinking distance

Answer 66

speed reaction time ( tired drunk drugs distracted all increase reaction time)

Question 67

breaking distance

Answer 67

distance taken to stop under the breaking force

Question 68

factors affecting breaking distance

Answer 68

speed / mass of car (both increase Ek of car) condition / quality of brakes traction between car & road (wet/icy)

Question 69

typical reaction time range

Answer 69

0.2 sec - 0.9 sec

Question 70

momentum

Answer 70

mass x velocity

Question 71

conservation of momentum

Answer 71

total momentum before an event = total momentum after an event

Question 72

when does a change in momentum occur

Answer 72

when a force acts on an object that is moving / able to move

Question 73

safety features in cars

Answer 73

air bags crumple zones seat belts

Question 74

safety features purpos

Answer 74

increase time it takes for momentum to be lost results in a lower force acting on the person reducing risk of harm